Area sources are defined by EPA as sources that emit less than 10 tons of a single hazardous air pollutant (HAP) or less than 25 tons of a combination of HAPs annually. National emission standards for these sources are being developed under EPA's Urban Air Toxics Strategy. Under the strategy, EPA has identified more than 30 toxic air pollutants. These pollutants were identified because Section 112(k)(3)(B) of the 1990 Clean Air Act (CAA) required EPA to identify at least 30 air toxics that pose the greatest potential public health threat in urban areas.

The EPA has identified 70 industry categories meeting the area source definition responsible for most of the emissions of the 30 toxic pollutants. Twenty-eight of these categories were regulated for emission reduction subject to national standards by June 2007. The remaining area source standards are under development. The EPA was put on a court ordered schedule to issue the area source rules listed under the strategy. Court orders issued in 2003 and 2006 resulted in the deadlines listed on EPA's web site.

For more information on EPA's development of area source standards, please click here.